1. Field of the Invention
The present invention relates to a video signal transmission system for an endoscope of the type having in its imaging system a solid state image sensor, such as a charge coupled device (CCD), a bucket brigade device (BBD), as referred to as a charge transfer device.
2. Description of the Prior Art
As well known in the art, an endoscope includes a viewing head which carries therein an imaging system, an illumination system, a forceps, a treating instrument, etc. A control section operates such systems and instruments of the viewing head while allowing image information picked up to be observed and recorded. The head and control sections are connected together by a flexible connecting section. A treating instrument of the head section often may take the form of a high frequency knife or scalpel. Where the endoscope employs a solid state image sensor in the imaging system in combination with the high frequency knife, the power supply line to the knife and the signal line from the imaging system are unavoidably arranged parallel to each other within the connecting section. Then, the endoscope suffers from a problem that noise is electromagnetically induced in an output signal of the imaging system by the high frequency current flowing through the power supply line to the knife, resulting in disturbance to the image which is monitored at the control section.
The disturbance to the image tends to appear itself as stripes or dots in a picture produced on a display which are objectionable for delicate operations in narrow cavities or openings and, in the worst cases, cause the operator to mislocate the surgical knife within such cavities.